Sodium Glutamate: Properties, Production, and Usage
Chemical Properties and Composition
A sodium salt of glutamic acid, an abundant naturally occurring non-essential amino acid. It exists as colorless, odorless crystals and is readily soluble in water. Its chemical formula is C5H8NNaO4. The glutamate ion plays a critical role in mammalian neurotransmission.
Production Methods
Historically produced through the hydrolysis of vegetable protein (e.g., wheat gluten). Modern production primarily relies on bacterial fermentation of carbohydrate sources, such as sugar beets, sugarcane, or corn. The fermentation process yields glutamic acid, which is then neutralized with sodium hydroxide to form the sodium salt.
Occurrence in Foods
Glutamate is naturally present in many foods, including tomatoes, cheeses, mushrooms, and seaweed. It contributes to the savory taste often referred to as "umami." Free glutamate, not bound within proteins, is what contributes most directly to this taste sensation.
Use as a Flavor Enhancer
Functions primarily as a flavor enhancer, amplifying existing savory flavors. It does not impart a distinct flavor of its own but rather balances and rounds out the overall taste profile of dishes. It is commonly used in processed foods, soups, sauces, and seasonings.
Regulation and Safety
Extensively studied and approved for use by regulatory agencies worldwide, including the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO). These organizations classify it as generally recognized as safe (GRAS) when used at normal levels.
Potential Sensitivities
Although generally recognized as safe, some individuals report sensitivity to it. This sensitivity is sometimes referred to as "symptoms complex," although controlled, double-blind studies have not consistently demonstrated a causal link between ingestion and reported symptoms. Reported symptoms vary widely and can include headache, flushing, sweating, and numbness.